How to lift a WJ

Old 03-24-2008, 09:24 PM
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Join Date: Feb 2008
Location: Durham, NC
Posts: 339
Year: 2003
Model: Grand Cherokee
Engine: 4.0L, 63mm TB, FIPK, Gibson Exhaust
Default How to lift a WJ

Thanks to Krupples26 for putting this together

This thread is to answer most of your questions regarding which parts are and are not necessary for a lift kit on a WJ (Jeep Grand Cherokee 1999-2004) as well as clarifying the many "will it fit" questions in regards to lift height, tire sizes, and the backspacing on your wheels. This thread is NOT for discussing which company makes the best lift kit at 3" or 4" or if you should get 3" coils versus UC springs and BB. Here you will find most of the pertinent information necessary to decipher what parts you need to buy in order to safely lift your jeep to your desired height. Suggested tire sizes and back spacing in respect to lift height is also addressed at the bottom of the page. Please keep in mind this information is specific for WJs (Jeep Grand Cherokees 1999-2004) and not your mom's Liberty or your uncle's ZJ.

Below are the parts that are recommended or required to lift a WJ to the specified height. "No" means the part is not required, "Yes" means that the part is necessary to lift to the specified height, and "Recommended" is, well... recommended for a better/more comfortable ride or may be necessary based on your individual preference. A description of each part can be found below the chart.

1. Sway bar links (front): the sway bar links in the front should be long enough so that the angle of the sides of the sway bar where it attaches to the links should form a 25-35 degree angle with the an imaginary line running parallel to the ground. For those of you that think you will be taking your vehicle off-road, JKS quick or quicker disconnects are recommended as they allow you to easily disconnect your sway bar, allowing the front axle more articulation to help overcome more difficult terrain.

2. Sway bar links (rear): the sway bar links in the rear should be long enough so that the angle of the sides of the sway bar where it attaches to the links should form a 0-10 degree angle with an imaginary line running parallel to the ground.

3. Track bar: the correct length of the track bar is the length from the upper and lower track bar mounts while the jeep is sitting on level ground after the installation of the lift kit. You should not have to manipulate the length from upper and lower track bar mounts by jacking up the suspension or body parts to shorten or lengthen the distance between the two mounts to make the track bar fit.

4. Shocks: shock length should be based on the size of your lift. Incorrect length of shocks will affect your overall ride quality and limit your flexibility in off camber situations, by limiting your length of up and down travel. A soft shock will ride nicely on the highway but will suffer in performance off road, where as a stiffer shock will have the opposite affect. A high quality shock can easily cost over $100 a piece while a cheaper shock simply used for DD can be found for $30.

5. Drop transfer case kit: a drop transfer case kit usually lowers your transfer case 1” (depends on manufacturer) by placing metal spacers in-between your transfer case cross member and the body of the vehicle. This helps to alleviate stress placed upon your pinion, drive shafts, and transfer case due to the increased angles of the driveline after lifting the suspension. Typically you can make it to around 4” of lift before considering dropping your transfer case. Another way to alleviate stress from the driveline is with a double cardan driveshaft (02-04 come from the factory with a double cardan driveshaft) as it adjusts to the steeper angle created after lifting the vehicle. As with any size lift, there will be increased stress on driveline components.

6-8. Control arms (for our purposes, 6-8 reference “short arms”, and are simply a longer version of the stock control arm. “Short arms” utilize the stock mounting locations on the body for your new, longer, “short arms”): as you increase the size of your springs and/or add spacers on top of your springs, the axles will start to sweep in towards the center of the vehicle as the length of your control arms determine where the axle will be placed in relation to the center of the wheel well. Longer front and rear control arms (short arms) will help push your axle back away from the center of the vehicle and back to the center of your wheel wells. Stock control arms are effective up to around 4” of lift, after which it is wise to upgrade to “short arms” or “long arms”.

9-10. Long arms (for our purposes, 9-10 reference “long arms”, and simply mean that the stock mounting locations on the body for the control arms are no longer used, and instead a new mounting bracket must either be welded or bolted to the body to serve as a new point of attachment for the long arms): long arms via the new attachment points greatly reduce body roll as they offer an amazing amount of stability and ride comfort. Long arms also serve to correct the geometry of suspension components. A front long arm upgrade will make driving a dream at any lift greater than 4.5”, and is highly recommended once you come close to the 5” or 5.5” mark. You may be able to scoot around upgrading to rear long arms when you are close to 6” of lift, but your ride quality will be much improved with the rear long arm upgrade. The rear long arm upgrade also does away with the jeeps A-arm, the triangular shaped bracket that secures to the top side of the axle and the underside of the vehicle. A rear long arm upgrade typically will require your exhaust system to be modified as the new attachment points and control arms will interfere with the stock routing of the exhaust.

11. A-arm spacer: this block of metal squeezes in-between the a-arm and the pumpkin on the axle. It allows more movement and flexibility in the rear axle and is suggested for lift heights just below 4” and all the way up to 6” or greater when used in conjunction with adjustable rear LCAs. An a-arm spacer is not needed when using rear long arms, as the a-arm is removed completely.

12. Steering stabilizer: a lift increases the pressure on steering components which are often too much for the wimpy stock SS. A high quality SS reduces the looseness of your steering wheel by preventing your wheel from jumping around as much.

13. Sway bar (rear): lowered vehicles feel tighter in turns because their center of gravity is lower; well once you lift your jeep you’ll feel more like a school bus going around turns. A bigger diameter sway bar offers more resistance as the jeep leans during a turn as well as helps to cure rear bump steer (tail wag).

One additional item to think about buying while you have your jeep torn apart are extended bumpstops as these will limit the travel of the axle towards the underside of the jeep, preventing your rotating tire from ripping the plastic out of your wheel well, and may also save your windshield washer fluid reservoir!

Below are common conversions for a 16x7" and 17x7" wheel and the suggested backspacing each tire size at various ride heights. For reference, stock wheels that measure 16x7 have 6” of backspacing, while 17x7.5 wheels have 6.25” backspacing.

*Heavy duty tie rods and drag links are recommended when moving into the 32" size tire and larger size tire.

Backspacing is important as it moves your rotating tire away from components that like to remain fixed. The front lower control arms and the rear shocks are often the items that become abused when backspacing is insufficient on larger diameter tires. Now a 16x7” wheel with 4” backspacing may sound like a full inch more backspacing than a 16x8” wheel with 5” backspacing, however due to the extra inch in width of the 8” wheel, it relocates the tire a half an inch. In essence, the difference between 4” bs on 7” width wheel vs 5” bs on 8” width is really only ½”. The diagram below illustrates how wheel width and backspacing effects where your tires are position. Each tire/wheel combo below is aligned at a fixed point to better reference the distance between the tire and the shock, and how much farther the tire has been pushed outside of the fender. I apologize for the pixilated picture as I am not very artistic. The picture is in the perspective of you standing behind your jeep looking at your driverside rear tire with your Superman vision so you can see through the outside layer of rubber and see the cross section of the rim and where it bolts on to the axle. The “Gained Fender Clearance over Stock 245 Tire” column does not mean that the value in the column represents how far the tire will stick out of the fender, but rather shows how far the tire has been displaced in the wheel well in comparison with a 245 tire. The measurement from tire to the shock is fairly accurate but obviously some shocks are much wider in diameter than others, and this is the measurement you should expect to see while the jeep is stationary on level ground. You should expect that distance to fluctuate while driving. I noticed while running a set of hydro shocks which were slightly larger than previous sized shocks, with a set of 245/75/16 Revos on stock rims, that when stationary I could barely fit my finger between the shock tube and the tire. Although there was evidence as to the tire rubbing on the shock via black rubber marks, supporting the fact that stationary clearance is not the same as clearance during transit. To examine backspacing in relation to tire width and lateral displacement, the height of the tire is irrelevant; the only thing the diagram is concerned with is tire width, wheel width, backspacing, the corresponding distance between the rear shock and the tire, and an estimated distance of how far the tire has moved outward in comparison with a typical 245 width tire.

Performance and city gas mileage will obviously suffer with larger diameter and heavier rims/tires. The chart below was found at is their computations and represents their work. This chart illustrates how your gas mileage will be affected by your tire size and gear ratio. The table can be used to get a rough idea on gear ratios (again, this chart is NOT specific to the WJ, but rather serves as an illustration). The colors represent ideal RPM's at highway speeds (65) for a given vehicle (not a WJ, I say again, NOT A WJ). For highway cruising and best fuel economy stay towards the yellow (2600 rpm), around town daily driving is color coded green (2800 rpm), and for better towing power or just more 4-low power use the ratios near the red (3100 rpm). In layman terms, if you run 30” tires and 3.73 gears, at 65 mph you generate 2715 RPM according to this chart. If you get some new rubbers in a size 33”, your new RPM at 65 mph is now 2469. It takes less RPMs to run a bigger tire than a smaller tire, but consequently your acceleration and power have dropped significantly. Therefore, to get that lost power back and maximum efficiency, you want to find what size gears is going to make your jeep perform like it did when you first bought it. So ideally with your new 33” tires you want to buy new gears that make you your 65mph highway RPM close to what it was at stock. To do this you walk your eyes down the 33” tire row to where you find a RPM that is close to 2715, in this case a set of 4.11 gears makes your RPM 2720.

For a more precise method, you can use the gear ratio calculator, which is the second calculator from the top found at Input your stock tire and gear settings (3.55 or 3.73), then input your new tire size and you can see what your recommended gear would be.

As you can see, life is simple prior to and around 4". However around the 4" mark things will start to get tricky and slightly more complicated. As more parts are needed to upgrade to and above 4", you will see the cost rise exponentially. You will see diminished ride quality on stock control arms. Upgrading to longer/adjustable control arms in the front and the rear and the addition of an a-arm spacer will increase the ride quality, while relocating the control arms via new mounting brackets and long arms will provide the best ride quality. A new and/or longer double cardan driveshaft may also be necessary to reduce driveline vibrations. Determine your goals for your jeep prior to lifting, and don't ever attempt to lift your jeep when money is tight. You best bet is to save up until you can build your rig the way you want it. Buying a 2" BB and a new set of tires right away based on your available funds and then upgrading 6 months later to what you really wanted just leaves you with a couple hundred dollars less than you would have had and an extra set of tires in your garage that are in great condition, yet are too small for your new height. Do it right the first time and you won't end up with an extra set of shocks, tires, control arms and sway bar links taking up space in your garage. Good luck, and the "Search" button at the top is your friend!

Helpful/suggested readings: for everything you need to know about the WJ answers and explanations of driveshafts and anything driveline related (pinion angles too!) a great compilation of tons of calculators

Disclaimer: if you feel that any of the information above is inaccurate in any way, or if you would like to add or see something added, please PM me with what you perceive to be incorrect and what you would like changed, or with what you would like to add or see added, and I will make the corresponding amendments as necessary. This post will be updated as needed. Thank you.

Thanks to Krupples26 for putting this together
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Old 03-24-2008, 10:36 PM
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Stickied, nice work
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